Mars Express ready for comet encounter

17 October 2014 - Europe's Mars orbiter and its scientific instruments will have a frontrow seat on Sunday when Comet Siding Spring grazes the Red Planet, skimming past at a little more than a third of the Moon's distance from Earth. Comet Siding Spring, discovered in January 2013, is less than a kilometre across and will pass Mars at 56 km/s, closing to within 139 500 km at 18:27 GMT (20:27 CEST) on 19 October. Initially, the comet and its envelope of gas and dust were predicted to pass much closer to Mars, posing a serious risk to the fleet of orbiting spacecraft. Later observations confirmed that the miss distance will, in fact, be more comfortable. ESA's teams flying Mars Express have spent months preparing for the encounter. "In 2013, we had very little information about the comet, which was still very far and faint. In the worst case, we expected the pass to be much closer, and the comet to be much more active," says Spacecraft Operations Manager Michel Denis.